Wireless Service Providers, or WISPs, strive to provide secured and seamless connectivity to the roaming users. Quality of existing communication gets degraded when a mobile is subjected to repeated handoff due to delay and packet loss. There are several transition events during the handoff such as discovery, configuration, authentication, security association, binding update and media redirection that contribute to the handoff delay and the associated packet loss. Several optimization techniques are being developed to address each of these handoff components. Currently, there are several types of mobility protocols, or mobile internet protocols (MIP), at different layers such as MIPv4, MIPv6, Host Identity Protocol (HIP), Session Initiation Protocol (SIP) and their faster variants such as Fast Mobile IPv6 (FMIPv6), and regional MIPv4 that can be used to take care of these handoff events. These mobility protocols are meant to reduce the packet loss and handoff delay during a mobile's change of connectivity from one point-of-attachment to another. However, these mobility protocols are not very suitable when a mobile's movement is confined to a domain and the communicating host is far off, or if both the communicating hosts are away from home. In order to reduce the delay due to binding update and associated one-way delay due to media transfer when a mobile's movement is confined to a specific domain, various local mobility management protocols have been designed. These include Cellular IP, Handoff Aware Wireless Access Internet Interface (HAWAII), Intra-Domain Mobility Management Protocol (IDNP), Hierarchical Mobile IPv6 (HMIPv6), among others. Proxy MIP (PMIP) is one such localized mobility protocol that helps to reduce the delay due to long binding update. It takes much of the burden away from the mobile and puts it on the access routers or proxy mobility agents within the network. Proxy mobility agents send the binding update to the home agents on behalf of the mobiles. Each mobile is anchored with a certain PMA (Proxy Mobility Agent) until it hands off to a new PMA.
In order to avoid the drawbacks associated with the global mobility protocols, such as MIP and SIP, that heavily depend upon mobility stack on the mobile node and optimize the mobility for a localized mobility domain, Network-based Localized Mobility Management (NETLMM) working group of the Internet Engineering Task Force (IETF) was created. NETLMM working group has created several Request for Comments documents, e.g., RFC 4830, RFC 4831, and RFC 4832, outlining the guidelines for designing a localized mobility protocol that will avoid the dependence upon the host to do binding update (BU) and limit the signaling updates when the mobile node moves within a domain. A few candidate protocols are currently being discussed, such as network-controlled local mobility and Proxy Mobile Internet Protocol (PMIP), including PMIPv4 and PMIPv6. These protocols are designed to take care of local mobility and, instead of depending upon a mobility stack in the mobile node, are controlled by the network elements in the edge routers.
PMIP, for example, does not use any mobility stack on the mobile node but rather uses Proxy Mobile Agents (PMAs) that can co-locate with the edge routers to help perform the mobility functions, such as the BU to the home agent (HA). As long as the mobile node moves within the same domain that has PMAs, the mobile node assumes that it is in a home link. The PMA is responsible for sending the proper mobile prefix as part of the router advertisement for stateless auto-configuration, or the PMA can also act as a Dynamic Host Configuration Protocol (DHCP) relay agent for stateful auto-configuration. In some cases, PMA can be referred to as a MAG (Mobility Access Gateway) and HA can be replaced by LMA (Local Mobility Agent). Thus, PMA and MAG can be used interchangeably and HA and LMA can be used interchangeably.
FIG. 1 describes the network elements and processes associated with PMIP operation. After the mobile node 10 connects to the new point-of-attachment as part of the initial bootstrapping process, or after the movement from the home network 12 to a new domain, e.g., Visited1 16, access is authenticated with the designated AAA server 14 (1: access initiation; 2: AAA Request/Reply). During this process, PMA1 18 sends the BU to the HA 20 with the address of the PMA that is specific to the home prefix of the mobile node 10, i.e., PMA1 18, (3: Proxy BU) and receives an acknowledgement (ACK) (4: Proxy ACK). In the absence of a pre-existing tunnel, this process helps to set up a tunnel, i.e., PMIP tunnel-1 22, between the HA 20 and the respective PMA (5: PMIP Tunnel-1). The mobile node 10 configures its address using the prefix included in the router advertisement and interface-id, which can be assigned by PMA1 18 or created by itself (6: home prefix advertisement).
FIG. 1 also illustrates the movement of the mobile node from one domain, Visited1 16, to another domain, Visited2 24. After the move, access is authenticated with the designated AAA server 14 (7: access initiation; 8: AAA Request/Reply). During this process, as before, PMA sends the BU to the HA 20 with the address of the PMA that is specific to the home prefix of the mobile node 10, i.e., PMA2 26, (9: Proxy BU), and receives a reply (10: AAA Query/Reply). If no tunnel exists, a tunnel, i.e., PMIP Tunnel-2 28, between the HA 20 and the respective PMA, i.e., PMA2 26, (11: PMIP Tunnel 2) is set up by the process.
The PMIP-based mobility protocol is preferred when mobility is confined within a domain and wireless service providers do not want to overload the mobile node's stack by setting up a tunnel between the mobile node and the HA. A tunnel is not desirable on the mobile node because it adds extra processing and bandwidth constraints to the wireless hop.
Although PMIP provides optimization compared to other global mobility protocols, it still needs improvement in certain areas such as route optimization. Route optimization reduces the delay due to media delivery between the two communicating mobile nodes by reducing the traversal distance between the communicating hosts. The present invention fulfills a need for route optimization techniques for PMIP that will further improve the effectiveness of PMIP for both intra-domain and inter-domain movement. Several scenarios can be realized by using route optimization technique. In all the scenarios, both the correspondent node and mobile belong to a PMIP domain. In one specific scenario, the mobile node and correspondent node belong to two different MAGs that are part of the same HA or LMA. In a second scenario, the mobile and the correspondent node belong to two MAGs (PMAs) that are under different HA (LMA). Thus, in this second case, the communicating nodes belong to two different PMIP domains, where the PMIP domains may belong to the same administrative domain or different one.